Add explicit require for Wikitext in WikiSlideParser
Add explicit require for Wikitext in WikiSlideParser

This will hopefully avoid the circular dependency error that showed up in P&E production

alpha721/WikiEduDashboard,KarmaHater/WikiEduDashboard,majakomel/WikiEduDashboard,alpha721/WikiEduDashboard,alpha721/WikiEduDashboard,sejalkhatri/WikiEduDashboard,WikiEducationFoundation/WikiEduDashboard,WikiEducationFoundation/WikiEduDashboard,sejalkhatri/WikiEduDashboard,WikiEducationFoundation/WikiEduDashboard,majakomel/WikiEduDashboard,WikiEducationFoundation/WikiEduDashboard,KarmaHater/WikiEduDashboard,alpha721/WikiEduDashboard,sejalkhatri/WikiEduDashboard,majakomel/WikiEduDashboard,sejalkhatri/WikiEduDashboard,WikiEducationFoundation/WikiEduDashboard,KarmaHater/WikiEduDashboard,sejalkhatri/WikiEduDashboard,majakomel/WikiEduDashboard,KarmaHater/WikiEduDashboard